There is no schematic, however, it will be added soon, please wait.
I have written scrolling code for 12f509:
YouTube - PIC LED MATRIX NUMBER SCROLLER
and experienced it considerably uncomfortable, due to stack level limitation.
the software stack will be used to gain one or two levels!
if you have explanation of scrolling methods, please write about it.
I am not limited to the 16f57, as outlined in the 1st post.
I also wrote a dot matrix scroller for 16f690, based on a non-proportional font:
YouTube - microcontroller LED matrix scroller - generic RISC code
actually I am afraid to implement the final "wires", means to send the font data to the matrix.
in the simulator, the text scroll works fine, but who can know it?
If there is some good feedback, I may consider to complete this code.
***
initially i've drawn the resistors on the sink side, not on the drive side.
using the LCX244 can have advantages:
-2.4 volts operation since it is CMOS
-faster assembly compared to transistors
-price can be considerably low if you buy a reel of SMD ICs, or a part of a reel (for instance 200 ICs).
-bit lines can be bundled
-about 1/2 of PCB space compared to transistors (there are also special SMD transistors which include base resistors already).
I am for instance using 1x LCX244 to drive a complete 4-digit 7-segment display, for this purpose, it is required to use two bitlines for each digit.
**broken link removed**
I have used transistors previously, particulary the 2n3906/2n3904.